Objective: Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors derived from adrenal or extra-adrenal locations, respectively. Upon suspicion of PPGL, specific metabolomic, molecular, biochemical, imaging, and histopathologic studies are performed to prove, localize, treat, and monitor disease progression. Improved diagnostic tools allow physicians to accurately diagnose PPGL, even in patients presenting with small (<1 cm) or biochemically silent tumors, which previously delayed proper detection and treatment.
Methods: This review outlines the most updated approach to PPGL patients and presents a new diagnostic protocol for physicians to increase earlier tumor identification and accurately assess metastatic behavior.
Conclusion: We present the most recent advances in genetics, epigenetics, metabolomics, biochemical, and imaging diagnoses of this rare tumor to properly assess disease, decide treatment options, and manage follow-up. We also elaborate on new therapeutic perspectives in these very rare neoplastic entities.
Abbreviations: ATRX = ATRX chromatin remodeler; ccRCC = clear cell renal cell carcinoma; c-MYC = MYC proto oncognene; CT = computed tomography; DOTATATE = DOTA-octreotate; EGLN1/2 = egl-9 family hypoxia inducible factor 1/2; EGLN2/PHD1 = egl-9 family hypoxia inducible factor 2; EPAS1/HIF2A = endothelial PAS domain protein 2/hypoxia-inducible factor 2α; ERK = extracellular signal-regulated kinase; HIFs = hypoxia-inducible factors; HIF-α = hypoxia-inducible factor alpha; HNPGLs = head and neck paragangliomas; 177Lu-DOTATATE = lutetium octreotate; MAX = myc-associated factor X; MDH2 = malate dehydrogenase; MIBG = metaiodobenzylguanidine; MN = metanephrine; MRI = magnetic resonance imaging; mTOR = mammalian target of rapamycin; NETs = neuroendocrine tumors; NF1 = neurofibromin 1; NMN = normetanephrine; PHD = prolyl hydroxylase domain protein; PI3K = phosphoinositide 3-kinase; PPGLs = pheochromocytoma and paragangliomas; PRRT = peptide receptor radionuclide therapy; Pvhl = von Hippel-Lindau protein; RAS = rat sarcoma oncogene; RET = rearranged during transfection proto-oncogene; SDH = succinate dehydrogenase; SDHA, -B, -C, -D = succinate dehydrogenase subunits A, B, C, D; SDHAF2 = succinate dehydrogenase complex assembly factor 2; SDHB, C, D = succinate dehydrogenase subunits B, C, D; SDHx = succinate dehydrogenase subunits; SSTRs = somatostatin receptors; VHL = von Hippel-Lindau.